Trees produce flowers of different colors due to developmental or genetic mutations
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Reference material confirms that biological mutations can lead to novel flower colors, and botanical literature demonstrates that tree and plant flower coloration is governed by genetic and developmental factors.
Several new peach (Prunus persica) flower types were discovered in an F2 segregating population from an open-pollinated, non-showy-flowered F1 seedling of ‘Helen Borchers’, a double-flowered ornamental cultivar. The novel flower types were white and red single-flowered, non-showy blooms, as well as double-flowered, non-showy red, pink, white, and yellow phenotypes. The double, non-showy flowers were very attractive, and resembled pom-pom chrysanthemums. Yellow flower color is unknown in peach. Flower type in the F2 family segregated ’3:1 for nonshowy (Sh_) vs. showy (shsh), for anthocyanin-present vs. anthocyanin-absent, and for pink (R_) vs. red (rr), independently. Flower petal number segregated at about 9:3:4 for classes single:semi-double:double. Although both parents were late flowering, the F1 was not. The F2 seedlings showed a wide range in time of flowering. Higher petal number was correlated with later bloom, although it is unclear whether this is due to linkage or developmental differences in the flowers with extra petals. These novel flower types might be useful as ornamentals, and for use in genetics and breeding studies. Microsatellite analysis of possible pollen donors revealed that ‘Oldmixon Free’, a nonshowy-flowered peach cultivar, was likely the pollen parent of the F1. Peach flowers normally have five separate, perigynous petals and sepals. Commercial peach fruit cultivars have pink flowers classified as one of two types, showy or non-showy, based on the corolla shape and size. Showy flowers have larger, overlapping petals that open nearly flat and hide the sepals. Non-showy flowers have smaller, narrower, slightly cupped petals with the sepals visible between them and the corolla also slightly cupped (campanulate). In non-showy flowers before anthesis, the anthers are often exposed and may dehisce, in contrast to showy flowers where the longer petals cover the anthers, inhibiting pollen shed before anthesis. Most of the oldest United States peach cultivars have non-showy flowers, which are the wild type. Many of the commercially important cultivars from the northern U.S. also have non-showy flowers. Although showy (shsh) is recessive to non-showy (Sh_) (Bailey and French, 1942), in recent decades more showy-flowered cultivars have been released, perhaps representing breeders’ bias toward showy flowers. The larger size of the unopened flowers makes them easier to emasculate and allows a longer window of availability for hand pollination. Also much of the recent breeding has been done in lower chilling regions, where much of the adapted germplasm was showyflowered. The Sh/sh locus has been mapped, but the morphological and cellular bases of the different types is unknown, as is their relative value to the plant. Pink is the characteristic peach flower color, but other colors have been reported (Bassi and Monet, 2008), including those designated white, dark pink, red, and variegated [with various combinations of white, pink and red, such as ‘Peppermint’ and ‘Candy Cane’ (Okie, 2013)]. Peaches with showy flowers having extra petals have been used as ornamentals for centuries, often in combination with novel growth forms like upright, weeping and/ or dwarf (Hedrick, 1917; Hu et al., 2005; Lammerts, 1945). These ‘‘double-flowered’’ forms can have numbers of extra petals ranging from a few to 75 petals (Lammerts, 1945). For example, ‘Candy Cane’ has 35–40 petals (Okie, 2013). Other floral parts such as pistils and sepals may be multiplied as well. Most highly double-flowered peaches, particularly those with multiple pistils, set little to no fruit, making them desirable as ornamental trees but difficult subjects for genetic studies. We find no report of non-showy flowers in colors other than shades of pink, nor with extra petals. Peach flower characteristics are useful in identifying cultivars, for verifying parents in crosses, and in genetic and linkage studies. Novel peach flower phenotypes can arise by mutation
Trees are long-lived plants characterized by the development of highly branched shoot systems. Along these structures, somatic mutations arise and may become fixed in reproductive tissues such as flowers and fruits. Because mature trees produce tens of thousands of terminal branches, limiting the accumulation of somatic mutations is critical to avoid mutational meltdown and inbreeding depression. Although recent evidence suggests that long-lived plants have evolved mechanisms that slow the buildup of somatic variants with age, the developmental basis for this remains unclear. Here, we derive a theoretical model linking crown development with cell lineage sampling to show that branching architecture strongly influences the accumulation of unique somatic mutations, often to the same extent as modulating the mutation rate itself. We find that tree forms that promote developmental path-sharing among branches restrict the spread of distinct cell lineages, lowering the crown-wide mutation burden by orders of magnitude even when mutation rates and branch numbers are held constant. This buffering effect suggests that branching strategies may evolve not only to optimize growth and resource allocation, but also to limit the genomic variation generated during ontogeny.
composed of two or more genetically distinct tissues, most commonly as a result of a graft and sometimes by mutations that occur during cell division or cellular
This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary of leaf morphology. For other related terms, see Glossary of phytopathology, Glossary of lichen terms, and List of Latin and Greek words commonly used in system
mutation
In times before the nature of genetic encoding was understood, mutation was regarded as an abrupt, and sometimes heritable, variation from the norm of a population; for example a plant might unexpectedly produce "double" flowers, a novel color, or a habit of growth uncharacteristic of the species or variety. Advances in genetics and molecular biology in the mid-twentieth century, showed that biological mutations comprise and reflect changes in the nucleic acid molecules that encode the genome of an organism or virus. The nucleic acid affected could be DNA in the chromosomes, or it could be extrachromosomal DNA (typically DNA in the mitochondria or chloroplasts). In RNA viruses a mutation would be a change to the genetic information that the RNA encodes.
The species Caesalpinia pulcherrima, which belongs to the Fabaceae family, is frequently used as a hedge or street tree in urban landscapes, parks and gardens. It flowers profusely, and the flowers, depending on the variety, may be pink, orange or yellow. As flower characteristics are essential for determining the commercial value of ornamental species, the main objective of this work was to identify polymorphisms in C. pulcherrima plants that produce flowers of different colors using RAPD molecular markers. For this study, 30 adult plants were randomly chosen on streets located in Jaboticabal city, São Paulo State, Brazil, and leaf samples were collected for DNA extraction. Among these trees, 20 have orange flowers, eight have yellow flowers and only two produce pink flowers. From the 140 tested RAPD primers, 94 primers amplified defined fragments that resulted in 246 bands, which were 100% monomorphic. Thus, a polymorphism was not detected by any of the primers tested. It was concluded that the RAPD technique is not an efficient method for detecting polymorphisms and that more specific molecular markers should be tested. Additionally, the morphological characteristic “flower color” may be controlled by several genes or by the association of them. O flamboyanzinho (Caesalpinia pulcherrima, Fabaceae) é muito utilizado como cerca-viva e na arborização de ruas, parques e jardins. De florescimento exuberante, suas flores podem apresentar coloração rosa, laranja ou amarela, confo
The species Caesalpinia pulcherrima, which belongs to the Fabaceae family, is frequently used as a hedge or street tree in urban landscapes, parks and gardens. It flowers profusely, and the flowers, depending on the variety, may be pink, orange or yellow. As flower characteristics are essential for determining the commercial value of ornamental species, the main objective of this work was to identify polymorphisms in C. pulcherrima plants that produce flowers of different colors using RAPD molecular markers. For this study, 30 adult plants were randomly chosen on streets located in Jaboticabal city, São Paulo State, Brazil, and leaf samples were collected for DNA extraction. Among these trees, 20 have orange flowers, eight have yellow flowers and only two produce pink flowers. From the 140 tested RAPD primers, 94 primers amplified defined fragments that resulted in 246 bands, which were 100% monomorphic. Thus, a polymorphism was not detected by any of the primers tested. It was concluded that the RAPD technique is not an efficient method for detecting polymorphisms and that more specific molecular markers should be tested. Additionally, the morphological characteristic “flower color” may be controlled by several genes or by the association of them.
Anthocyanins, the pigments that give rise to blue, purple, red, and pink colors in many flowers and fruits, are produced by the deeply conserved flavonoid biosynthesis pathway. The regulation of this pathway is thus fundamental for species differences in color across flowering plants, and a growing body of evidence implicates MYB transcription factors as key players activating or suppressing the production of different pigments. Nevertheless, the potential role of MYBs genes in determining the type of pigment produced (as opposed to the overall amount) is unknown. Here, we demonstrate that a lineage of R2R3 MYBs that is closely related to well-known flavonol regulators (MYB12 members in subgroup 7) is the primary determinant of the shift from blue to red flowers in the genus Iochroma. Similar to its ortholog in Capsicum, this Iochroma MYB12-like gene controls the expression of flavonoid-3'-hydroxylase, the pathway branch point between red and blue pigments, and when down-regulated, results in redirection of flux toward red pigments. These results underscore the importance of transcription factor evolution in generating phenotypic novelty as well as the competitive nature of interactions among flavonoid pathway branches. In addition, our study demonstrates the effectiveness of RNAseq of segregating populations, in combination with other lines of evidence, for identifying novel functional variation.
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